I am confused by the transformer on the schematic
Input #5 I understand - its sourced from the 9+V supply and is in direct relation to the DAC output. I can also stomach the fact that there are three outputs and when JP6 is enabled the output voltage is presumably tapped and equally split to power a tripolar toy.
What I am not understanding is why inputs 4 and 6 appear to be dependent on more pins from the processor (PB2, PB3 and PA0). If anything I’d have expected to see just one other grounded input pin, since all the necessary juice appears to be coming into pin 5.
Can anyone help explain what’s going on?